A binding machine includes: a main handle configured to accommodate a staple; a staple driver supported by the main handle and configured to drive the staple; and a clincher arm rotatably attached to the main handle and including a clincher, the clincher being configured to clinch the staple driven by the staple driver. The staple driver includes: a driving portion that extends in a direction away from the main handle and is configured to drive the staple toward the clincher, and an attachment portion with which the driving portion is attached to the main handle, and the attachment portion extends in a longitudinal direction of the main handle from a side edge of the driving portion.